In the use of word processors, WYSIWYG-type HTML editors, graphic tools or other tools, it is necessary to “select” an object to perform editing operations such as copying, cutting, pasting, or deleting of an object or changing of the attribute values thereof. One of the simplest ways to do so is to use mouse clicks for selection. However, in the case of a Web page, for example, where many objects are arranged in an overlapped or nested manner, it is difficult to click on a target object due to a narrow area for clicking, resulting in repeated failure in clicking on the target object, and an alternative way, such as designation of a rectangular area, keyboard operation or the like, may be required. Therefore, there is a demand for a method enabling easy selection of a target object even in such a case where the objects are arranged in a complicated manner.
Some methods enabling selection of an object from among those complicatedly arranged on a display screen are known, which include an object stack in WebArt Designer included in IBM® Homepage Builder™ (Non-Patent Document 1), and a layer palette in Adobe® Photoshop® (Non-Patent Document 2). The object stack and the layer palette are each for displaying items corresponding to all the objects arranged on the display screen in a specific location (object stack or layer palette) in the form of a list for selection. In the list, the items are displayed to indicate the stacked order of the corresponding objects, and when a mouse is clicked on a specific item among them, the corresponding object is selected. In addition, there is known a technique where the object elements are displayed in the form of a tree, and when a mouse is clicked on an element on the tree, the corresponding object is selected on the editor.
While all the objects are listed for display in each of the conventional techniques described above, there is also known a technique where only the objects satisfying a prescribed condition are extracted for display in a list. See Japanese Unexamined Patent Publication (Kokai) No. 2002-366974. According to this known technique, the objects through which a straight line connecting the view point and the cursor position transmits are extracted as selection candidate objects and listed for display in a list dialog box. See also “Method for selecting a plurality of objects at the same time in WebArt Designer”
(http://www-06.ibm.com/jp/domino01/swhc/esupport.nsf/all/hpb0720) and“Summary of Layer Palette”(http://help.adobe.com/ja_JP/Photoshop/10.0/help.html?content=WSfd1234e1c4b69f30ea53e41001031ab64-78e1.html.□
With the method of listing and displaying all the objects, the location for displaying the list is fixed, and thus, if the location is far from a selected object, it would be necessary to move the mouse a relative long distance. Further, since all the objects are displayed on the list, if the number of objects increases, it may be troublesome to select a desired object. With the method disclosed in Japanese Unexamined Patent Publication (Kokai) No. 2002-366974, although such trouble may be saved, the selection candidates are determined according to whether the straight line connecting the view point and the cursor position transmits through the objects, and thus, if a user wishes to designate a small object hidden behind a large object as a selection candidate, a plurality of clicking operations would be necessary.